1. Technical Field
This invention relates to an image processing apparatus for storing an image data inputted from image data inputting means in storage means as a plural image data in various resolution, and making proper use of them for the printing and the visual display.
2. Description of the Prior Art
It has been proposed an image data processing apparatus wherein an image data inputted from image data inputting means such as an image scanner is stored into storage means such as a magnetic disc, an optical disc, or a magneto-optical disc, and the image data fetched from the storage means on demand is outputted from image data outputting means such as a printer.
The Japanese patent laid-open publication No. 8-180180 discloses an image data processing apparatus wherein an image data inputted from image data inputting means is stored in storage means as a plural image data of various resolution, which are made proper use for the printing the displaying and so on.
FIG. 12 is a schematic block diagram showing an example of the above-mentioned image data processing apparatuses. In the image data processing apparatus shown in FIG. 12, a multi-valued image data inputted from image data inputting means 10 such as an image scanner is binarized as a standard image data of high resolution for the printing by a binarization circuit 11, and then stored in storage means 17 such as a hard disc.
A multi-valued image data inputted from the image data inputting means 10 has the resolution of 400 DPI, for example. The multi-valued image data is stored in the storage means 17 without changing the resolution as described above, and on the other hand the multi-valued image data is converted to an image data for the displaying (which is called xe2x80x98a display image dataxe2x80x99 hereinafter) changed to low resolution, for example, 200 DPI, by a resolution converting circuit 13, and binarized by a second binarization circuit 14, and then stored in an image data memory 15 temporarily. First the standard image data is compressed and coded (represented by xe2x80x9cencodedxe2x80x9d hereinafter) by an encoding circuit 16. After the processing the display image data is outputted from the image data memory 15, and encoded by the encoding circuit 16, and then stored in the storage means 17 corresponding to the standard image data.
The standard image data of high resolution stored in the storage means 17 is decoded by a decoding circuit 19 and inputted to a printer 20 for the printing.
A display screen 21 has the facility for displaying the 256 gradation because 8 bits are used for each color of RGB Red, Green, Blue), but the resolution of the display screen 21 is small relatively, for example, more or less 200 DPI. Accordingly, the display image data of the above low resolution is to be utilized mainly for the displaying on the display screen 21 in case of the searching of image data.
If it is arranged that a plural image data of various resolution are available selectively, an user can browse the preview of the outlined image data (image data of low resolution) in case of the expansion and displaying of image data, and then image data of high resolution can be obtained later on Accordingly, in case of searching image data while browsing them on the display screen 21, it is possible to skip over an unnecessary processing of expanding the image data of high resolution. Therefore it is possible to arrange an image data processing apparatus with efficient operational performance.
In case there is remarkable difference between the resolution of the printer 20 and that of the display screen 21, when the image data is displayed on the display screen 21 in the same resolution as the printer 20, a part of the image data can be displayed only. Therefore, if the apparatus is constituted so as to be able to use the above-mentioned display image data, the great advantage can be given.
In case of filing an original of an intermediate-tone image data such as a photograph, however, when the original is processed by the simplified binarization for converting to binary digit, that is 1 or 0, according to a specific threshold value, it brings the remarkable deterioration of picture quality. Accordingly, the original is arranged to be binarized by the pseudo intermediate-tone processing such as the error diffusion method of reproducing the intermediate-tone in the proportion of white and black per unit area.
But the pseudo intermediate-tone processing causes the frequent change of black and white in the intermediate density area having a large change of density, so that the compression rate of the encoded data could decline. (For example, since the encoded data changing black and white periodically such as xe2x80x9c1111000011110000. . . xe2x80x9d, in other words when a high density or a low density area repeats itself for several times, can be represented by the information of the repeat of 4 white and 4 black, the compression rate is high.)
Namely, there is a problem that the conventional image data processing apparatus must be provided with a mass memory because the compression rate for the encoding is low.
This invention is proposed to solve the above-mentioned problems in the conventional apparatus. And the objects are to reduce the size of the image data in the intermediate density area by deteriorating the gradation performance of the image data in said area to a specific degree and thereby to increase the compression rate at the encoding and to improve the storage efficiency at the filing.
Namely, in order to achieve the above objects, as shown in FIG. 1, an image data processing apparatus in the invention is presumed that a multi-valued image data inputted from image data inputting means 10 is encoded not only as a standard image data but also as a display image data of the lower resolution than that of the standard image data, and both of them are stored in storage means 17, and the display image data stored in the storage means 17 is decoded and then inputted to browsing means 21 such as a display screen.
And the image data processing apparatus is provided at the preceding step of resolution converting means 13 for obtaining the display image data with first gradation converting means 12 for converting the intermediate density area of the multi-valued image data to a specific high density or specific low density.
And as shown in FIG. 5, the image data processing apparatus in the invention can be provided with second gradation converting means 23 for converting the intermediate density area in the multi-valued image data obtained from the image data inputting means 10 to the specific high density or the specific low density.
Therefore, it is possible in the image data processing apparatus in the invention to reduce the size of the image data in the intermediate density area by deteriorating the gradation performance of the image data in said area to a specific degree without touching the picture quality and thereby to increase the compression rate at the encoding and to improve the storage efficiency at the filing.
Moreover as shown in FIG. 7, the image data processing apparatus can comprise image data transferring means 30 and 31 for transferring online the decoded display image data, and browsing means 33 for displaying the display image data transferred from the image data transferring means 30 and 31. And otherwise the apparatus can comprise image data transferring means 30 and 31 for transferring online the encoded data corresponding to the display image data stored in the storage means 17, decoding means (not shown, for decoding the encoded data transferred from the image data transferring means 30 and 31, and browsing means 33 for displaying the decoded image data.
To the contrary, the image data processing apparatus as an off-line state shown in FIG. 8 can comprise image data writing means 40 for storing the decoded display image data in a removable storage media, image data reading means 41 for reading the display image data acquired from the removable storage media, and browsing means 43 for displaying the display image data thus read. And otherwise the apparatus can comprise image data writing means 40 for storing in a removable storage media the encoded image data corresponding to the display image data stored in the storage means 17, image data reading means 41 for reading the encoded image data from the removable storage media, decoding means (not shown) for decoding the encoded image data thus read, and browsing means 43 for displaying the decoded image data thus decoded.
On the other hands, as the image data inputting means in the image data processing apparatus it is possible to use at least one among an image scanner 10 for reading an original image data optically, a fax modem 50 for receiving an image data via dedicated line or a public line, or a printer interface 51 for receiving an image data via dedicated line or a network.